class Dog:
    legs_num = 4
    has_hair = True
    has_tail = True

    def bark(self):
        print("狗狂吠")

    def bite(self):
        print("狗咬人")

    def fetch(self):
        print("狗捡球")

alex = Dog()
peiQi = Dog()
print(id(alex))
print(id(peiQi))
print(alex == peiQi)